Obtaining bone marrow samples for diagnostic purpose in medicine requires insertion of an instrument into a marrow space following penetration into a hard cortical bone that surrounds the marrow space. Traditionally it is done by pushing in a hollow needle that has a cutting edge or a cutting tip at its distal end. Usually two specimens, i.e., solid piece of marrow and liquid aspirate, are required for accurate assessment of potential disorders in the bone marrow. The majority of biopsies of bone marrow require at least two separate insertions of the needle, with each for a solid and a liquid sample, respectively. Acquisition of a solid piece of marrow requires threading a small linear fragment of marrow into a hollow tubular space of a needle whereas liquid marrow requires negative suctioning of the marrow into the tubular space of the needle for sampling.
Although it sounds simple and has been done in such a way for almost every patient, the requirement of a minimum of two separate insertions into hard bones has resulted in doubling of discomfort and pain on the part of patients and operator fatigue on the part of medical personnel. Consequently some physicians favor an increase in local anesthetics and sometimes heavy sedation of patients to alleviate their discomfort. Furthermore, some patients who would have a low platelet count are exposed to an increase in a risk of bleeding from the biopsy sites, and some with a low white blood cell count may have an increase in a risk of infection, when theoretically compared to a single insertion acquisition of marrow samples.
Another drawback of acquisition of solid marrow samples comes from frequent loss of the threaded sample in the hollow tubular shaft of a needle, which is yet adhered to a main body of the marrow at the distal tip of the hollow tubular shaft of a biopsy needle. Since the tubular shaft of the needle is straight and hollow, threaded-in samples are routinely lost in whole or in part when the needle is withdrawn unless the threaded-in sample is broken off at an angle from the main body of the marrow, held tight inside the hollow tube of the needle or captured inside the hollow tube. Furthermore, some diseases of the marrow such as leukemia tend to have a fragile marrow sample that gets fragmented easily. The loss of solid marrow samples necessitates repeating insertion of the needle until an adequate amount of sample is obtained, which obviously exacerbates the aforementioned problems. Wide circumferential and whirling rotation of the biopsy needle along the longitudinal axis to break off the sample has been universally accepted as one technique of biopsy yet it causes additional discomfort to patients.
Several patents have disclosed methods and devices to capture samples that are threaded in the hollow tube of the biopsy needle. Some devices utilize insertable or indented internal threads located on an inner wall of biopsy needle close to a cutting tip and some other devices have one or a plurality of capturing devices installed inside a tubular space of the needle. These devices have improved efficiency of procurement of samples but oftentimes suffer from a lack of consistency in mechanical performance. Biopsy needles with internal threads tend to have broken fragments of samples especially when the needle has not penetrated a marrow space long enough or when a cortical bone is very hard. Helical internal threads require uni-directional circumferential rotation all the way through from a beginning of insertion of the needle into a bone to a retrieval of the needle. Incidental rotations of the needle to an opposite direction may loose a sample back to a main body of the marrow. Consequently, it is not uncommon that well-trained physicians resort back to the old yet venerable Jamshidi biopsy device for consistency of mechanical performance over a wide range of patients.
The current invention aims at solving these two technical challenges, one to reduce discomfort and pain of patients and the other to dependably secure samples, by sequential acquisition of solid marrow sample followed by liquid marrow sample upon a single entry into target bone marrow and by fail-safe directional grip on solid marrow samples.